White LEDs are commonly used in smart phone, TV and car headlight applications
With bold claims on energy efficiency, Typhon says that in less than three years the power of commercially available disinfection-range UV-LEDs has more than quadrupled.
This raises the question of whether such claims stack up and also links to Haitz’s Law, which is critical when discussing UV-LED scale up.
Named after scientist Roland Haitz (1935-2015), the law predicts that LEDs will halve in cost and double in light output every two years.
Looking back, Haitz’s law is apparent over the last 40 years. For example, in the 1970s the first LEDs to be established were red. Then, due to development in wavelength throughout the rainbow of colours, blue LEDS became commercial in 1990s.
From blue came the development of white LEDs, from which there was an explosion in the market for car headlights, phone screens and TV were developed. Finally, from blue came UV and the application for water disinfection.
Pearls of wisdom
Following this pattern, it was in 2012 when AquiSense introduced its UV-C LED PearlAqua system for water disinfection. This year it expects to ship over 40,000 units and the company is also supplying its LED system for the Flint schools initiative, backed by the Musk Foundation.
Rather than jumping into the metaphorical deep end with a larger system, Lawal says the company “started small and worked up”, tracking the development of LED technology.
“We knew if we solved the engineering and manufacturing challenges with novel small systems, we could already be profitable by the time the big ones were ready,” he says. “So it's just a matter of waiting for the power and the price to hit a certain target.”
The company has just supplied a UV-LED system to an oil and gas project “with several hundred gallons of capacity”, according to Lawal and will be rolling out a larger scale municipal pilot in California later this year.
UV-LED proponents often talk about energy as well as maintenance benefits. One of the claims is that as LEDs emit light rather than heat into the water, it avoids the problem of fouling and subsequent need for cleaning, as required with mercury lamps.
“The systems are engineered so the light surface is cool and you don’t get fouling in the same way,” says Lawal. “That’s a massive fundamental difference. This is why we’re doing these pilots – we haven’t quantified the benefit yet. It’s fair to say there’s a theoretical benefit with LEDS that will be proven out over the next year or two.”
Other UV experts however throw more caution to the wind when it comes to disruption claims associated with LEDs.
“It’s a little bit of a red herring when it comes to maintenance claims of LEDs,” says Mark Kustermans, municipal market manager for Trojan Technologies.
“Anything that has water, you’re going to have some fouling on that surface. Fouling will occur regardless of whether its UV-LED or it’s a lamp. I think cleaning and maintaining the UV the source will still remain a critical feature.”
Established in 1977, TrojanUV won its first municipal wastewater project in Tillsonburg, Ontario. Today it has over 10,000 municipal installations using lamp technology.
“We recognise that UV-LEDs will be part of our future,” adds Kustermans. “We have assembled a team to evaluate and develop the next generation of UV products using LEDs. We are interested in collaborating with leading UV-LED players and we’re talking to many. We will apply UV-LEDS where it makes sense for our customers.”
The municipal market manager believes the use of UV-LED systems for municipal scale applications is currently “premature” and that he sees current applications in the point of use and point of entry space.
He also believes the price tipping point for LED technology remains several years away for broader market adoption.
LED weak points
Others believe despite their weaknesses, it’s a question of not if but when UV-LED will be scaled up and adopted.
“Their weak points have meant LEDs are still some way away from elbowing aside mercury lamps, at least in larger plants,” adds Paul O'Callaghan, CEO of BlueTech Research.
“These include a relatively high cost and low power output, particularly within the UVC wavelength, which is the one important for water disinfection.”
Material selection and chip manufacturing have been a particular focus of R&D, as characteristics such as substrate and dislocation density ultimately influence LED efficiency and output, he says.
Paul O'Callaghan adds: “Nevertheless, progress in lowering costs and boosting power output has been too slow for any serious commercial impact at a large-scale or industrial level. Taken together, it seems inevitable that large scale UV-LEDs will become commercially viable and widely adopted at large scale – it’s just a question of when.”
Market impact and scale